There exist graphics presentation systems which have the capability of blending colors to arbitrary shades between two end-point colors and for creating intermediate shapes between two end shapes. This has several useful purposes, one of which, for example, is that graphic artists can use the systems to make a smooth graduation between two colors or shapes for highlights or shading or for whatever purpose they might have in mind. The drawback to most of these packages is their inflexibility.
In order to create a blend between two shapes, (or a graduation in color) a user must pick the two end shapes that are wanted, select the derived number of intermediate steps between the two end shapes and then the program would generate the intermediate shapes. In the prior art, however, to make a change, the user had to go back and manually purge the intermediate shapes, then make the changes that are desired and then manually call for the intermediate shapes to be regenerated. Thus, experimental changes to the intermediate shapes (or colors, or other attributes such as line width or angle of a graduated fill) are cumbersome and inconvenient, especially if a user desires to make several experimental changes.
Systems that perform this type of shading and blending are, for example, Aldus Freehand 2.0, which was released to the public in 1988. That program allowed a user to draw two shapes and then designate a number of computer-generated intermediate shapes between them. However, if the user later decided that he/she is not satisfied with the intermediate shapes because the color (or shape) of one of the source shapes was not what was wanted, the user would have to pick out all of the intermediate shapes, manually remove them, alter one or both of the source shapes (or their color), go back and select the two source shapes, and then respecify how many intermediate steps he/she wanted to use to blend the source colors and shapes. This same cumbersome process is required for any change that the user might want to make to one of the source paths. For instance, each time the user wanted to change the shape or color of one or both of the source paths, or wanted to change the number of intermediate steps generated to effect a smooth blending of shapes, the user must repeat the same cumbersome process.
Thus, a need exists in the art for a system in which a user need not manually remove all of the intermediate images when it is desired to change the blending (or shapes) between the two end shapes.
A further need exists in the art for a graphic presentation system which allows a user to simply change one or more of the end shapes (or colors) and then automatically readjust all of the computer-generated shapes (or colors) without user involvement and without requiring the user to first remove the original computer-generated shapes (or colors).